Mutations
- Created by: EmmaMorris2003
- Created on: 25-01-21 10:13
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- Mutations
- Mutagenic agents
- Increase the rate of mutations and probability of mutation occurring
- Examples: UV radiation, ionising radiation, some cheicals and some viruses
- Deletion
- Nucleotide is lost from the normal DNA sequence
- Involves a frame shift
- A frame shift at the start of the nucleotide sequence has a greater effect than at the end.
- A frame shift at the start=amino acids in the primary structure of the polypeptide chain are likely to be different
- Triplets will be different=amino acids coded for will be different=polypeptides will be different
- Leads to a non-functioning protein-could alter the phenotype
- Triplets will be different=amino acids coded for will be different=polypeptides will be different
- Substitution
- Nucleotide is replaced by a nucleotide with a different base. 3 consequences of a substitution
- Missense mutation-base change which results in a different amino acid being coded for
- Non-sense mutation-base change which results in the formation of 1/3 stop codons
- Silent mutation-substituted base, although different, still codes for the same amino acid
- Nucleotide is replaced by a nucleotide with a different base. 3 consequences of a substitution
- Addition
- Involves a frame shift
- A frame shift at the start of the nucleotide sequence has a greater effect than at the end.
- A frame shift at the start=amino acids in the primary structure of the polypeptide chain are likely to be different
- Triplets will be different=amino acids coded for will be different=polypeptides will be different
- Leads to a non-functioning protein-could alter the phenotype
- Triplets will be different=amino acids coded for will be different=polypeptides will be different
- An extra nucleotide is inserted so an extra base is added to the sequence
- Involves a frame shift
- Benefits of a mutation
- Lead to new versions of proteins that help an organism to adapt to changes in their environment
- Essential for evolution
- They increase an organisms chance of survival and reproduction
- Mutagenic agents
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